Honestly I think both of them pair well with different expansion strategies, but I think xenophobe is the more difficult choice, by the numbers.
Xenophile diplomacy lets you more easily keep your enemies close until such time as you're ready to take them on (should you decide to), so from a realpolitische perspective, xenophile gives you a more flexible foreign policy, I think.
It's better to have just the purgers and zealots hate you initially, and the rest of your neighbors like you or be indifferent to you, if your goal is to remain independent and grow your borders. Even just one additional neighboring enemy can spell the end of the game for you, early-on.
Xenophobes can do the same, of course, but the xenophobe penalty to relations makes it just that much harder, and the purge penalties to relations, at least as of 1.4, are even more severe.